Nitric oxide concentration in the gas phase of the gastrointestinal tract in man

• Published in: European journal of clinical investigation Vol. 27; no. 12; pp. 992 - 996
• Main Authors: KASTNER, J., PFEFFEL, F., RAJEK, A., PEZAWAS, T., HIESMAYR, M., EICHLER, H.-G.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01-12-1997; Blackwell
• Subjects: Adult; Aged; Biological and medical sciences; Digestive System - chemistry; Endoscopy; Female; Gases - analysis; Gastrointestinal Contents - chemistry; gastrointestinal tract; Humans; Hydrogen-Ion Concentration; intensive care; Investigative techniques, diagnostic techniques (general aspects); Luminescent Measurements; Male; Medical sciences; Middle Aged; Miscellaneous. Technology; nitric oxide; Nitric Oxide - analysis; Pathology. Cytology. Biochemistry. Spectrometry. Miscellaneous investigative techniques; stomach; Assay; Human; Emergency department; Nitric oxide; Digestive diseases; Intestinal disease; Diagnosis; Endoscopy; Gas phase; Technique; Gastric disease
• ISSN: 0014-2972; 1365-2362
• DOI: 10.1046/j.1365-2362.1997.2120761.x

Nitric oxide (NO) has been implicated in various aspects of physiological regulation in the gastrointestinal tract. Hence, measurement of luminal NO concentrations is of interest for studying physiological and pathophysiological alterations in NO generation; however, at present, no reliable measurement techniques are available. Here we describe novel approaches for measurement of NO concentrations directly in the gas phase of the stomach and colon in healthy subjects and patients. Studies were conducted in young healthy volunteers (n = 13), intensive care patients (n = 8) and patients undergoing gastroscopy (n = 8) or colonoscopy (n = 8). NO concentrations were measured by chemolumininescence detection in air obtained through a nasogastric tube, after inflation into the stomach of a defined volume of air, or directly in the air suctioned from the endoscope. The mean NO concentration obtained from the stomach of healthy volunteers studied under baseline conditions was 18.0 ± 2.8 (SEM) p.p.m. Day‐to‐day reproducibility of NO measurements was high. Tube feeding with a nitrite‐ and nitrate‐free feeding solution left gastric NO concentrations unchanged, but standardized bicycle exercise caused an ≈30% decrease in NO levels. NO concentrations in intensive care patients were ≈2 log cycles lower than in healthy volunteers. NO levels in the colon were similar to those in the stomach. We have described two readily applicable techniques for direct, uncontaminated measurement of NO concentrations in the lumen of the gastrointestinal tract. Our finding of a striking reduction in gastric NO concentrations in intensive care patients requires further study.